All anti-virus anti-malware software is rubbish, they just use md5 hash checks. The malware authors have been getting past that for years by using polymorphic installers and the anti-virus community has not yet managed to deal with that.
The problem is Windows.
The sad part is that there's no money in browser jacking anyway, if you speak to the people who've done it. Unfortunately for as long as people think there is money in it then they will try.